RCTUIManagerObserverCoordinator: new way to subscribe for granular notifications from UI Manager

Reviewed By: majak

Differential Revision: D4868591

fbshipit-source-id: 24a09ffa3e69dec5ce1f0a8715c7e4701d781996

Libraries/NativeAnimation/RCTNativeAnimatedModule.h

@@ -11,6 +11,7 @@
 #import <React/RCTEventDispatcher.h>
 #import <React/RCTEventEmitter.h>
 #import <React/RCTUIManager.h>
+#import <React/RCTUIManagerObserverCoordinator.h>
 
 #import "RCTValueAnimatedNode.h"
 

Libraries/NativeAnimation/RCTNativeAnimatedModule.m

@@ -28,7 +28,7 @@ RCT_EXPORT_MODULE();
 {
   [_nodesManager stopAnimationLoop];
   [self.bridge.eventDispatcher removeDispatchObserver:self];
-  [self.bridge.uiManager removeUIManagerObserver:self];
+  [self.bridge.uiManager.observerCoordinator removeObserver:self];
 }
 
 - (dispatch_queue_t)methodQueue
@@ -48,7 +48,7 @@ RCT_EXPORT_MODULE();
   _preOperations = [NSMutableArray new];
 
   [bridge.eventDispatcher addDispatchObserver:self];
-  [bridge.uiManager addUIManagerObserver:self];
+  [bridge.uiManager.observerCoordinator addObserver:self];
 }
 
 #pragma mark -- API
@@ -196,6 +196,8 @@ RCT_EXPORT_METHOD(removeAnimatedEventFromView:(nonnull NSNumber *)viewTag
   [_preOperations addObject:operation];
 }
 
+#pragma mark - RCTUIManagerObserver
+
 - (void)uiManagerWillFlushUIBlocks:(RCTUIManager *)uiManager
 {
   if (_preOperations.count == 0 && _operations.count == 0) {

React/Modules/RCTUIManager.h

@@ -59,24 +59,7 @@ RCT_EXTERN NSString *const RCTUIManagerDidRemoveRootViewNotification;
  */
 RCT_EXTERN NSString *const RCTUIManagerRootViewKey;
 
-@class RCTUIManager;
+@class RCTUIManagerObserverCoordinator;
-
-/**
- * Allows to hook into UIManager internals. This can be used to execute code at
- * specific points during the view updating process.
- */
-@protocol RCTUIManagerObserver <NSObject>
-
-/**
- * Called before flushing UI blocks at the end of a batch. Note that this won't
- * get called for partial batches when using `unsafeFlushUIChangesBeforeBatchEnds`.
- * This is called from the UIManager queue. Can be used to add UI operations in that batch.
- */
-- (void)uiManagerWillFlushUIBlocks:(RCTUIManager *)manager;
-
-@end
-
-@protocol RCTScrollableProtocol;
 
 /**
  * The RCTUIManager is the module responsible for updating the view hierarchy.
@@ -139,17 +122,6 @@ RCT_EXTERN NSString *const RCTUIManagerRootViewKey;
  */
 - (void)prependUIBlock:(RCTViewManagerUIBlock)block;
 
-/**
- * Add a UIManagerObserver. See the RCTUIManagerObserver protocol for more info. This
- * method can be called safely from any queue.
- */
-- (void)addUIManagerObserver:(id<RCTUIManagerObserver>)observer;
-
-/**
- * Remove a UIManagerObserver. This method can be called safely from any queue.
- */
-- (void)removeUIManagerObserver:(id<RCTUIManagerObserver>)observer;
-
 /**
  * Used by native animated module to bypass the process of updating the values through the shadow
  * view hierarchy. This method will directly update native views, which means that updates for
@@ -192,6 +164,12 @@ RCT_EXTERN NSString *const RCTUIManagerRootViewKey;
  */
 - (void)setNeedsLayout;
 
+/**
+ * Dedicated object for subscribing for UIManager events.
+ * See `RCTUIManagerObserver` protocol for more details.
+ */
+@property (atomic, retain, readonly) RCTUIManagerObserverCoordinator *observerCoordinator;
+
 @end
 
 @interface RCTUIManager (Deprecated)

React/Modules/RCTUIManager.m

@@ -33,6 +33,7 @@
 #import "RCTScrollableProtocol.h"
 #import "RCTShadowView.h"
 #import "RCTUtils.h"
+#import "RCTUIManagerObserverCoordinator.h"
 #import "RCTView.h"
 #import "RCTViewManager.h"
 #import "UIView+React.h"
@@ -225,7 +226,6 @@ static UIViewAnimationOptions UIViewAnimationOptionsFromRCTAnimationType(RCTAnim
   NSDictionary *_componentDataByName;
 
   NSMutableSet<id<RCTComponent>> *_bridgeTransactionListeners;
-  NSMutableSet<id<RCTUIManagerObserver>> *_uiManagerObservers;
 }
 
 @synthesize bridge = _bridge;
@@ -306,7 +306,7 @@ RCT_EXPORT_MODULE()
   _rootViewTags = [NSMutableSet new];
 
   _bridgeTransactionListeners = [NSMutableSet new];
-  _uiManagerObservers = [NSMutableSet new];
+  _observerCoordinator = [RCTUIManagerObserverCoordinator new];
 
   _viewsToBeDeleted = [NSMutableSet new];
 
@@ -723,20 +723,6 @@ BOOL RCTIsUIManagerQueue()
   }
 }
 
-- (void)addUIManagerObserver:(id<RCTUIManagerObserver>)observer
-{
-  dispatch_async(RCTGetUIManagerQueue(), ^{
-    [self->_uiManagerObservers addObject:observer];
-  });
-}
-
-- (void)removeUIManagerObserver:(id<RCTUIManagerObserver>)observer
-{
-  dispatch_async(RCTGetUIManagerQueue(), ^{
-    [self->_uiManagerObservers removeObject:observer];
-  });
-}
-
 /**
  * A method to be called from JS, which takes a container ID and then releases
  * all subviews for that container upon receipt.
@@ -1159,10 +1145,19 @@ RCT_EXPORT_METHOD(dispatchViewManagerCommand:(nonnull NSNumber *)reactTag
     [self addUIBlock:uiBlock];
   }
 
+  [_observerCoordinator uiManagerWillPerformLayout:self];
+
   // Perform layout
   for (NSNumber *reactTag in _rootViewTags) {
     RCTRootShadowView *rootView = (RCTRootShadowView *)_shadowViewRegistry[reactTag];
     [self addUIBlock:[self uiBlockWithLayoutUpdateForRootView:rootView]];
+  }
+
+  [_observerCoordinator uiManagerDidPerformLayout:self];
+
+  // Properies propagation
+  for (NSNumber *reactTag in _rootViewTags) {
+    RCTRootShadowView *rootView = (RCTRootShadowView *)_shadowViewRegistry[reactTag];
     [self _amendPendingUIBlocksWithStylePropagationUpdateForShadowView:rootView];
   }
 
@@ -1175,9 +1170,7 @@ RCT_EXPORT_METHOD(dispatchViewManagerCommand:(nonnull NSNumber *)reactTag
     }
   }];
 
-  for (id<RCTUIManagerObserver> observer in _uiManagerObservers) {
+  [_observerCoordinator uiManagerWillFlushUIBlocks:self];
-    [observer uiManagerWillFlushUIBlocks:self];
-  }
 
   [self flushUIBlocks];
 }

React/Modules/RCTUIManagerObserverCoordinator.h

@@ -0,0 +1,67 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <UIKit/UIKit.h>
+
+#import <React/RCTViewManager.h>
+
+/**
+ * Allows to hook into UIManager internals. This can be used to execute code at
+ * specific points during the view updating process.
+ * All observer handler is called on UIManager queue.
+ */
+@protocol RCTUIManagerObserver <NSObject>
+
+@optional
+
+/**
+ * Called just before the UIManager layout views.
+ * It allows performing some operation for components which contain custom
+ * layout logic right before regular Yoga based layout. So, for instance,
+ * some components which have own React-independent state can compute and cache
+ * own intrinsic content size (which will be used by Yoga) at this point.
+ */
+- (void)uiManagerWillPerformLayout:(RCTUIManager *)manager;
+
+/**
+ * Called just after the UIManager layout views.
+ * It allows performing custom layout logic right after regular Yoga based layout.
+ * So, for instance, this can be used for computing final layout for a component,
+ * since it has its final frame set by Yoga at this point.
+ */
+- (void)uiManagerDidPerformLayout:(RCTUIManager *)manager;
+
+/**
+ * Called before flushing UI blocks at the end of a batch. Note that this won't
+ * get called for partial batches when using `unsafeFlushUIChangesBeforeBatchEnds`.
+ * This is called from the UIManager queue. Can be used to add UI operations in that batch.
+ */
+- (void)uiManagerWillFlushUIBlocks:(RCTUIManager *)manager;
+
+@end
+
+/**
+ * Simple helper which take care of RCTUIManager's observers.
+ */
+@interface RCTUIManagerObserverCoordinator : NSObject <RCTUIManagerObserver>
+
+/**
+ * Add a UIManagerObserver. See the `RCTUIManagerObserver` protocol for more info.
+ * References to observers are held weakly.
+ * This method can be called safely from any queue.
+ */
+- (void)addObserver:(id<RCTUIManagerObserver>)observer;
+
+/**
+ * Remove a `UIManagerObserver`.
+ * This method can be called safely from any queue.
+ */
+- (void)removeObserver:(id<RCTUIManagerObserver>)observer;
+
+@end

React/Modules/RCTUIManagerObserverCoordinator.m

@@ -0,0 +1,70 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "RCTUIManagerObserverCoordinator.h"
+
+#import "RCTUIManager.h"
+
+@implementation RCTUIManagerObserverCoordinator {
+  NSHashTable<id<RCTUIManagerObserver>> *_observers;
+}
+
+- (instancetype)init
+{
+  if (self = [super init]) {
+    _observers = [[NSHashTable alloc] initWithOptions:NSHashTableWeakMemory capacity:0];
+  }
+
+  return self;
+}
+
+- (void)addObserver:(id<RCTUIManagerObserver>)observer
+{
+  dispatch_async(RCTGetUIManagerQueue(), ^{
+    [self->_observers addObject:observer];
+  });
+}
+
+- (void)removeObserver:(id<RCTUIManagerObserver>)observer
+{
+  dispatch_async(RCTGetUIManagerQueue(), ^{
+    [self->_observers removeObject:observer];
+  });
+}
+
+#pragma mark - RCTUIManagerObserver
+
+- (void)uiManagerWillPerformLayout:(RCTUIManager *)manager
+{
+  for (id<RCTUIManagerObserver> observer in _observers) {
+    if ([observer respondsToSelector:@selector(uiManagerWillPerformLayout:)]) {
+      [observer uiManagerWillPerformLayout:manager];
+    }
+  }
+}
+
+- (void)uiManagerDidPerformLayout:(RCTUIManager *)manager
+{
+  for (id<RCTUIManagerObserver> observer in _observers) {
+    if ([observer respondsToSelector:@selector(uiManagerDidPerformLayout:)]) {
+      [observer uiManagerDidPerformLayout:manager];
+    }
+  }
+}
+
+- (void)uiManagerWillFlushUIBlocks:(RCTUIManager *)manager
+{
+  for (id<RCTUIManagerObserver> observer in _observers) {
+    if ([observer respondsToSelector:@selector(uiManagerWillFlushUIBlocks:)]) {
+      [observer uiManagerWillFlushUIBlocks:manager];
+    }
+  }
+}
+
+@end

React/React.xcodeproj/project.pbxproj

@@ -951,6 +951,12 @@
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+		59EB6DBB1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h in Headers */ = {isa = PBXBuildFile; fileRef = 59EB6DB91EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h */; };
+		59EB6DBC1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h in Headers */ = {isa = PBXBuildFile; fileRef = 59EB6DB91EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h */; };
+		59EB6DBD1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m in Sources */ = {isa = PBXBuildFile; fileRef = 59EB6DBA1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m */; };
+		59EB6DBE1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m in Sources */ = {isa = PBXBuildFile; fileRef = 59EB6DBA1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m */; };
+		59EB6DBF1EBD6FFC0072A5E7 /* RCTUIManagerObserverCoordinator.h in Copy Headers */ = {isa = PBXBuildFile; fileRef = 59EB6DB91EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h */; };
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 		59FBEFB21E46D91C0095D885 /* RCTScrollContentShadowView.m in Sources */ = {isa = PBXBuildFile; fileRef = 59FBEFAD1E46D91C0095D885 /* RCTScrollContentShadowView.m */; };
@@ -1078,6 +1084,7 @@
 			dstPath = include/React;
 			dstSubfolderSpec = 16;
 			files = (
+				59EB6DC01EBD70130072A5E7 /* RCTUIManagerObserverCoordinator.h in Copy Headers */,
 				59B1EBCA1EBD47520047B19B /* RCTShadowView+Layout.h in Copy Headers */,
 				3D7BFD351EA8E43F008DFB7A /* RCTDevSettings.h in Copy Headers */,
 				3D7BFD331EA8E433008DFB7A /* RCTPackagerClient.h in Copy Headers */,
@@ -1271,6 +1278,7 @@
 			dstPath = include/React;
 			dstSubfolderSpec = 16;
 			files = (
+				59EB6DBF1EBD6FFC0072A5E7 /* RCTUIManagerObserverCoordinator.h in Copy Headers */,
 				59B1EBC91EBD46250047B19B /* RCTShadowView+Layout.h in Copy Headers */,
 				3D7BFD311EA8E41F008DFB7A /* RCTPackagerClient.h in Copy Headers */,
 				3D7BFD291EA8E37B008DFB7A /* RCTDevSettings.h in Copy Headers */,
@@ -1799,6 +1807,8 @@
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 		59A7B9FB1E577DBF0068EDBF /* RCTRootContentView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTRootContentView.h; sourceTree = "<group>"; };
 		59A7B9FC1E577DBF0068EDBF /* RCTRootContentView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTRootContentView.m; sourceTree = "<group>"; };
+		59EB6DB91EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTUIManagerObserverCoordinator.h; sourceTree = "<group>"; };
+		59EB6DBA1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTUIManagerObserverCoordinator.m; sourceTree = "<group>"; };
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@@ -2042,12 +2052,6 @@
 		13B07FE01A69315300A75B9A /* Modules */ = {
 			isa = PBXGroup;
 			children = (
-				CF2731BE1E7B8DE40044CA4F /* RCTDeviceInfo.h */,
-				CF2731BF1E7B8DE40044CA4F /* RCTDeviceInfo.m */,
-				130E3D861E6A082100ACE484 /* RCTDevSettings.h */,
-				130E3D871E6A082100ACE484 /* RCTDevSettings.mm */,
-				369123DF1DDC75850095B341 /* RCTJSCSamplingProfiler.h */,
-				369123E01DDC75850095B341 /* RCTJSCSamplingProfiler.m */,
 				E9B20B791B500126007A2DA7 /* RCTAccessibilityManager.h */,
 				E9B20B7A1B500126007A2DA7 /* RCTAccessibilityManager.m */,
 				13B07FE71A69327A00A75B9A /* RCTAlertManager.h */,
@@ -2058,6 +2062,10 @@
 				58114A4E1AAE93D500E7D092 /* RCTAsyncLocalStorage.m */,
 				13D033611C1837FE0021DC29 /* RCTClipboard.h */,
 				13D033621C1837FE0021DC29 /* RCTClipboard.m */,
+				CF2731BE1E7B8DE40044CA4F /* RCTDeviceInfo.h */,
+				CF2731BF1E7B8DE40044CA4F /* RCTDeviceInfo.m */,
+				130E3D861E6A082100ACE484 /* RCTDevSettings.h */,
+				130E3D871E6A082100ACE484 /* RCTDevSettings.mm */,
 				13D9FEE91CDCCECF00158BD7 /* RCTEventEmitter.h */,
 				13D9FEEA1CDCCECF00158BD7 /* RCTEventEmitter.m */,
 				13B07FE91A69327A00A75B9A /* RCTExceptionsManager.h */,
@@ -2066,6 +2074,8 @@
 				B233E6E91D2D845D00BC68BA /* RCTI18nManager.m */,
 				352DCFEE1D19F4C20056D623 /* RCTI18nUtil.h */,
 				352DCFEF1D19F4C20056D623 /* RCTI18nUtil.m */,
+				369123DF1DDC75850095B341 /* RCTJSCSamplingProfiler.h */,
+				369123E01DDC75850095B341 /* RCTJSCSamplingProfiler.m */,
 				13D9FEEC1CDCD93000158BD7 /* RCTKeyboardObserver.h */,
 				13D9FEED1CDCD93000158BD7 /* RCTKeyboardObserver.m */,
 				13F17A831B8493E5007D4C75 /* RCTRedBox.h */,
@@ -2078,6 +2088,8 @@
 				13B07FEE1A69327A00A75B9A /* RCTTiming.m */,
 				13E067481A70F434002CDEE1 /* RCTUIManager.h */,
 				13E067491A70F434002CDEE1 /* RCTUIManager.m */,
+				59EB6DB91EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h */,
+				59EB6DBA1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m */,
 			);
 			path = Modules;
 			sourceTree = "<group>";
@@ -2627,6 +2639,7 @@
 				3D302F811DF828F800D6DDAE /* RCTNavItemManager.h in Headers */,
 				135A9C061E7B0F7800587AEB /* RCTJSCHelpers.h in Headers */,
 				3D302F841DF828F800D6DDAE /* RCTPointerEvents.h in Headers */,
+				59EB6DBC1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h in Headers */,
 				3D302F851DF828F800D6DDAE /* RCTProgressViewManager.h in Headers */,
 				3D302F861DF828F800D6DDAE /* RCTRefreshControl.h in Headers */,
 				3D302F871DF828F800D6DDAE /* RCTRefreshControlManager.h in Headers */,
@@ -2834,6 +2847,7 @@
 				3D80DA401DF820620028D040 /* RCTTouchEvent.h in Headers */,
 				3D80DA411DF820620028D040 /* RCTTouchHandler.h in Headers */,
 				13134C8C1E296B2A00B9F3CB /* RCTMessageThread.h in Headers */,
+				59EB6DBB1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.h in Headers */,
 				3D80DA421DF820620028D040 /* RCTURLRequestDelegate.h in Headers */,
 				3D80DA431DF820620028D040 /* RCTURLRequestHandler.h in Headers */,
 				3D80DA441DF820620028D040 /* RCTUtils.h in Headers */,
@@ -3305,6 +3319,7 @@
 				2D3B5ECF1D9B096F00451313 /* RCTFont.mm in Sources */,
 				2D3B5ED51D9B098000451313 /* RCTModalHostViewController.m in Sources */,
 				2D3B5EBC1D9B092600451313 /* RCTKeyboardObserver.m in Sources */,
+				59EB6DBE1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m in Sources */,
 				2D3B5E971D9B089000451313 /* RCTBridge.m in Sources */,
 				2D3B5EA21D9B08BA00451313 /* RCTModuleMethod.m in Sources */,
 				2D3B5E9B1D9B08A000451313 /* RCTFrameUpdate.m in Sources */,
@@ -3514,6 +3529,7 @@
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 				13CC8A821B17642100940AE7 /* RCTBorderDrawing.m in Sources */,
 				83CBBA511A601E3B00E9B192 /* RCTAssert.m in Sources */,
+				59EB6DBD1EBD6FC90072A5E7 /* RCTUIManagerObserverCoordinator.m in Sources */,
 				13AF20451AE707F9005F5298 /* RCTSlider.m in Sources */,
 				130443A21E3FEAA900D93A67 /* RCTFollyConvert.mm in Sources */,
 				58114A501AAE93D500E7D092 /* RCTAsyncLocalStorage.m in Sources */,